Liquid gaging system multiplexing

Claim 2

In a liquid gaging system, apparatus for monitoring individual sensors one at a time, comprising: a plurality of sensors, each sensor providing a range of liquid measurement signals relating to liquid depth at a particular location in a tank; and means for selectively monitoring individual sensors one at a time for a unique signal in the range relating to actual liquid depth at the particular location in the tank, the means for selectively monitoring being connected to the sensors.

Claim 3

The apparatus of claim 1 wherein at least one of the sensors comprises a capacitive probe.

Claim 4

The apparatus of claim 2 wherein the means for selectively monitoring comprises means for selectively providing individual sensors with an excitation signal.

Claim 5

The apparatus of claim 3 wherein the means for selectively providing further comprises means for grounding predetermined sensors not receiving the excitation signal, the means for grounding being connected to the means for selectively providing.

Claim 6

The apparatus of claim 2, 3, or 4 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 7

The apparatus of claim 1 wherein the means for selectively monitoring comprises means for selectively providing individual sensors with an excitation signal.

Claim 8

The apparatus of claim 6 wherein the means for selectively providing further comprises means for grounding predetermined sensors not receiving the excitation signal, the means for grounding being connected to the means for selectively providing.

Claim 9

The apparatus of claim 7 wherein at least one of the sensors comprises a capacitive probe.

Claim 10

The apparatus of claim 8 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 11

In a liquid gaging system, apparatus for selectively monitoring individual sensors one at a time, comprising: a plurality of sensor systems, each sensor system comprising a plurality of sensors applicable to a particular tank, each sensor providing a range of liquid measurement signals relating to liquid depth at a particular location in a particular tank; and means for selectively monitoring individual sensors one at a time for a unique signal in the range relating to actual liquid depth at the particular location in the tank, the means for selectively monitoring being connected to the sensors.

Claim 12

In a liquid gaging system, apparatus for selectively monitoring individual sensors one at a time, comprising: a plurality of sensor systems, each sensor system comprising a plurality of sensors applicable to a particular tank, each sensor providing a range of liquid measurement signals relating to liquid depth at a particular location in a particular tank; and means for selectively monitoring individual sensors one at a time for a unique signal in the range relating to actual liquid depth at the particular location in the tank, the means for selectively monitoring being connected to the sensors.

Claim 13

The apparatus of claim 10 wherein at least one of the sensors comprises a capacitive probe.

Claim 14

The apparatus of claim 11 wherein the means for selectively monitoring comprises means for selectively providing individual sensors with an excitation signal.

Claim 15

The apparatus of claim 12 wherein the means for selectively providing further comprises means for grounding predetermined sensors not receiving the excitation signal, the means for grounding being connected to the means for selectively providing.

Claim 16

The apparatus of claim 13 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 17

The apparatus of claim 10 wherein the means for selectively monitoring comprises means for selectively providing individual sensors with an excitation signal.

Claim 18

The apparatus of claim 15 wherein the means for selectively providing further comprises means for grounding predetermined sensors not receiving the excitation signal, the means for grounding being connected to the means for selectively providing.

Claim 19

The apparatus of claim 16 wherein at least one of the sensors comprises a capacitive probe.

Claim 20

The apparatus of claim 17 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 21

In a liquid gaging system, apparatus for monitoring individual probes one at a time, comprising: a plurality of probe systems, each probe system comprising a plurality of probes for mounting in a tank; means for selectively providing an individual probe in a probe system with an excitation signal, the means for selectively providing being connected to the probes; means for selectively grounding predetermined probes not receiving the excitation signal, the means for selectively grounding being connected to the probes; and means for selecting a probe system for liquid measurement and for monitoring the individual probe for a unique signal in a range of signals provided by the probe, each signal relating to an actual liquid depth at the particular location in the tank, the means for selecting a probe system being connected to the probe systems.

Claim 22

In a liquid gaging system, apparatus for monitoring individual probes one at a time, comprising: a plurality of probe systems, each probe system comprising a plurality of probes for mounting in a tank; means for selectively providing an individual probe in a probe system with an excitation signal, the means for selectively providing being connected to the probes; means for selectively grounding predetermined probes not receiving the excitation signal, the means for selectively grounding being connected to the probes; and means for selecting a probe system for liquid measurement and for monitoring the individual probe for a unique signal in a range of signals provided by the probe, each signal relating to an actual liquid depth at the particular location in the tank, the means for selecting a probe system being connected to the probe systems.

Claim 23

The apparatus of claim 19 wherein at least one of the probes comprises a capacitive probe.

Claim 24

The apparatus of claim 20 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 25

Apparatus for monitoring an individual sensor in a multiple-tank, multiple-sensor liquid gaging system, comprising: a plurality of capacitive sensors for mounting in a plurality of tanks, there being a plurality of capacitive sensors for each tank, each capacitive sensor having a first electrode and a second electrode, each capacitive sensor providing a liquid measurement signal variable in dependence on the portion of the sensor immersed in liquid and on the dielectric constant of the liquid, the sensors for a particular tank comprising a particular sensor system; excitation signal means having an output for providing an excitation signal having a voltage; excitation multiplexer means for selectively controlling application of the excitation signal to the first electrode of a predetermined sensor in each sensor system, the excitation multiplexer means having a first input connected to receive the excitation signal and having a plurality of outputs, each output being connected to the first electrode of a predetermined capacitive sensor in each sensor system; a plurality of input amplifier means for converting current to voltage, each input amplifier means having an input, there being for each sensor system an input of an input amplifier means connected to the second electrode of each capacitive sensor in the sensor system, the input amplifier means also having an output; and input multiplexer means for selectively monitoring a predetermined probe system, the input multiplexer means having a plurality of first inputs, each first input being connected to the output of a predetermined input amplifier means, the input multiplexer means also having an output for providing a signal corresponding to the predetermined sensor in the predetermined sensor system.

Claim 26

Apparatus for monitoring an individual sensor in a multiple-tank, multiple-sensor liquid gaging system, comprising: a plurality of capacitive sensors for mounting in a plurality of tanks, there being a plurality of capacitive sensors for each tank, each capacitive sensor having a first electrode and a second electrode, each capacitive sensor providing a liquid measurement signal variable in dependence on the portion of the sensor immersed in liquid and on the dielectric constant of the liquid, the sensors for a particular tank comprising a particular sensor system; excitation signal means having an output for providing an excitation signal having a voltage; excitation multiplexer means for selectively controlling application of the excitation signal to the first electrode of a predetermined sensor in each sensor system, the excitation multiplexer means having a first input connected to receive the excitation signal and having a plurality of outputs, each output being connected to the first electrode of a predetermined capacitive sensor in each sensor system; a plurality of input amplifier means for converting current to voltage, each input amplifier means having an input, there being for each sensor system an input of an input amplifier means connected to the second electrode of each capacitive sensor in the sensor system, the input amplifier means also having an output; and input multiplexer means for selectively monitoring a predetermined probe system, the input multiplexer means having a plurality of first inputs, each first input being connected to the output of a predetermined input amplifier means, the input multiplexer means also having an output for providing a signal corresponding to the predetermined sensor in the predetermined sensor system.

Claim 27

The apparatus of claim 22 wherein: at least one of the capacitive sensors in each sensor system comprises a capacitive probe for use in providing a wetted sensor length signal; and one of the capacitive sensors in at least one sensor system comprises a capacitive dielectric sensor.

Claim 28

The apparatus of claim 23 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 29

The apparatus of claim 22 wherein a predetermined number of the capacitive sensors each comprise a capacitive probe having an essentially uniform capacitance per unit length.

Claim 30

The apparatus of claim 23, 24 or 25 wherein: the apparatus further comprises a microcomputer for providing input control signals to control to input multiplexer means; and the input multiplexer means also has a plurality of second inputs for receiving the input control signals.

Claim 31

The apparatus of claim 23, 24 or 25 wherein: the apparatus further comprises a microcomputer for providing excitation control signals to the excitation multiplexer means; and the excitation multiplexer means also has a plurality of second inputs for receiving the excitation control signals.

Claim 32

The apparatus of claim 22 wherein: the apparatus further comprises a microcomputer for providing input control signals to control to input multiplexer means; and the input multiplexer means also has a plurality of second inputs for receiving the input control signals.

Claim 33

The apparatus of claim 28 wherein: at least one of the capacitive sensors in each sensor system comprises a capacitive probe for use in providing a wetted sensor length signal; and one of the capacitive sensors in at least one sensor system comprises a capacitive dielectric sensor.

Claim 34

The apparatus of claim 29 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 35

The apparatus of claim 28 wherein a predetermined number of the capacitive sensors each comprises a capacitive probe having an essentially uniform capacitance per unit length.

Claim 36

The apparatus of claim 22 wherein: the apparatus further comprises a microcomputer for providing excitation control signals to the excitation multiplexer means; and the excitation multiplexer means also has a plurality of second inputs for receiving the excitation control signals.

Claim 37

The apparatus of claim 32 wherein: at least one of the capacitive sensors in each sensor system comprises a capacitive probe for use in providing a wetted sensor length signal; and one of the capacitive sensors in at least one sensor system comprises a capacitive dielectric sensor.

Claim 38

The apparatus of claim 33 wherein the capacitive probe has an essentially uniform capacitance per unit length.

Claim 39

The apparatus of claim 32 wherein a predetermined number of the capacitive sensors each comprise a capacitive probe having an essentially uniform capacitance per unit length.